718 Commits

Author	SHA1	Message	Date
Thomas Harte	dd428c5d4d	Slightly relaxed time it takes to recognise vertical sync; considered what to do about reviving proper vertical sync but then gave up.	2015-07-24 23:56:25 -04:00
Thomas Harte	cea2580000	Upped internal precision a little.	2015-07-24 23:36:44 -04:00
Thomas Harte	ecb2898bd5	The overall architecture of who has responsibility for what is now very askew but: the CRT now outputs a tightly packed short buffer, with the probable OpenGL destination in mind. So it's now all fixed arithmetic internally. CRTFrame is reduced to a plain C struct with the intention that the OpenGL view will take responsibility for it and stop doing the back-and-forth sprint on getting buffer data. The Atari 2600 now outputs explicit blanks rather than level blacks for its border, so that it's easier visually to debug the CRT in its form as far as it has currently progressed: to drawing lines where the cathode ray gun would run while outputting pixel. I note that I'm still not quite getting vertical sync right yet — I'm just accepting it anywhere in teh frame — but that should be an easy fix.	2015-07-24 23:29:45 -04:00
Thomas Harte	d72287a776	Looked up normal retrace time (it's a lot less than 16µs and 26 scanlines — more like 7 and 10) and that the visible portion of a line is defined to start about 12 µs after the start of hsync, put the first two numbers into my CRT to make that more accurate, then derived a newer guess about what the Atari 2600 does for each of its 228 cycles. The text version of a frame is now looking pretty good. So it's probably time to hit OpenGL and the OS X side of things. Though I'll have a quick look to find out whether I can learn the exact real Atari 2600 timings before moving on.	2015-07-23 19:24:25 -04:00
Thomas Harte	33c06baffa	Explicitly separated vertical and horizontal sync event tracking, so as explicitly to be able to handle a coincidental simultaneous occurrence of both. Also for clarity.	2015-07-23 18:53:18 -04:00
Thomas Harte	5203f31bf4	Reintroduced a console examination of the output runs being received after fixing a failure to complete or restart frames over in the CRT; weirdly it seems that sync is being obeyed but raster position is off. So work to do.	2015-07-22 20:45:10 -04:00
Thomas Harte	065050115f	Made an attempt to switch to a triple-buffering scheme for CRT outputs, with an eye towards asynchronicity.	2015-07-22 20:33:20 -04:00
Thomas Harte	b503e13380	Fix one: vertical scan speed was failing to allow for the number of cycles in a line.	2015-07-22 18:56:35 -04:00
Thomas Harte	963cb2f6fb	Attempted to switch to slightly more meaningful names within the CRT and implemented a delegate to investigate output. Working on it.	2015-07-22 18:15:18 -04:00
Thomas Harte	908c171d2d	Commented the heck out of this thing, to put my thoughts in order if nothing else.	2015-07-21 16:37:39 -04:00
Thomas Harte	a1a1b15d18	Made a quick attempt to accumulate a list of detected output runs. Which means finally having to specify normal frame height. I'm already at too many magic formulae though, so this will need proper revision when I'm next awake. Definitely my horizontal position advancement is way off.	2015-07-20 23:18:56 -04:00
Thomas Harte	4fa315ab4d	This looks a lot closer to correct. The loss of horizontal sync during vertical sync is odd but the two should be fully decoupled in here. I'll have to check. Probably I've got something wrong. There are approximate sinusoidals when re-establishing sync, so that's promising as to the flywheel.	2015-07-20 21:58:32 -04:00
Thomas Harte	4695295dd1	Made complete attempt at sync discrimination. But I seem somehow to be locking such that horizontal sync is in the middle of the line. Obviously my flywheel is at fault somehow.	2015-07-20 21:43:00 -04:00
Thomas Harte	4e4c082a05	Made some minor attempt at proper sync response. I think I've gone way off piste and overcomplicated it.	2015-07-19 23:43:22 -04:00
Thomas Harte	4a1e9fe2a8	Rephrased the CRT as owning an arbitrary number of buffers and vending storage space for pixel output. That much better maps to potential implementations of this thing in GLSL, with ES 2.0's limitations kept in mind.	2015-07-19 21:21:34 -04:00
Thomas Harte	7df5025eef	Started sketching out the delegate interface that will allow a branch from the CRT into whatever native display system is used by a particular platform.	2015-07-19 18:32:42 -04:00
Thomas Harte	6f78ecdc9c	Made first genuine attempt at outputting a meaningful CRT stream. Which shows some significant errors. So work to do.	2015-07-19 16:48:14 -04:00
Thomas Harte	2d0f861474	Incoming: a 'CRT' class, to receive information intended for a cathode ray tube. To decode sync, etc.	2015-07-19 13:36:27 -04:00